10 Reasons Your Dog Has Diarrhea

Simple Solution or Serious Issue?

Let’s talk about your dog’s “business.” Have you recently noticed that your dog has diarrhea? There are numerous reasons why dogs have diarrhea, some of which could indicate a serious health issue.

Dogs and Diarrhea

If your dog has diarrhea, then you’re already familiar with the signs: loose, liquid-like stool, with frequent trips outside to relieve the bowel. Diarrhea in dogs can occur suddenly and last as long as a day or two up to a few weeks or months.

If your dog’s diarrhea persists for more than a day, dehydration can be a concern. Diarrhea that lasts longer can be an indication that your dog has an underlying health issue.

So, what are some of the reasons your dog may have diarrhea?

1Change in Kibble

A sudden change in diet can upset your dog’s stomach and intestinal tract, leading to diarrhea. The usual rule of thumb is a gradual change if you are switching your dog’s food. The general recommendation is to slowly increase your dog’s new food while decreasing the current food over the course of one week. Think of your dog’s food bowl like the shape of a pie with equal slices. Each day swap out one “slice” of old current kibble with new kibble.

2. Ate Spoiled Food

Some veterinarians refer to this as “garbage gut.” It means your dog ate something (maybe from the trash can or table scraps) that has caused an upset stomach. While most cases of garbage gut are mild, it depends on what was consumed: your dog could develop pancreatitis which is more serious and requires veterinary care.

Raw meat and fish

3.  Bacterial Infection and Viral Diseases

Your dog’s diarrhea could be caused bacteria found in raw or improperly cooked meats, meat left sitting out for awhile or in decaying vegetables. Studies show dogs can pick up a bacterial infection if kenneled with another dog that has it. Diarrhea can occur every two to four weeks and could be ongoing for years. Check your dog’s stool for shiny mucus on the surface and fresh blood.

Viral diseases such as Parvovirus (especially in puppies), distemper, coronavirus and other rotaviruses also cause foul-smelling diarrhea. These viral diseases are highly contagious and can be life threatening; signs include lethargy, vomiting, lack of appetite, fever and, in distemper, coughing. Immediate veterinary care is recommended.   

4.  Intestinal Parasites

Intestinal parasites are most commonly found in water sources outside (puddles, ponds, stagnant water) and in animal stool. If you dog drinks contaminated water or eats stool, there’s a chance he may have consumed parasitic cysts shed in the stool that open the door for parasites to live in his intestine. This will cause diarrhea which can look frothy, greasy, have a great deal of mucus and carry a significantly strong odor. Your veterinarian will treat your dog to remove the parasite.

5. Ate Toxic Substance

Wild mushrooms

One of the first signs your dog may have eaten something poisonous or toxic is frequent diarrhea.

Toxic culprits can include plants such as daffodils, ivy, bluebells, mistletoe, holly, and honeysuckle. Wild mushrooms, sunscreen lotion, human medications and vitamins (especially vitamin D), ice packs, silica gel sachets found in moisture-sensitive goods, chalk and charcoal can harm your dog.

Read more about toxic plants and pets and toxic medications for pets.

6. Allergic Reaction

If your dog is having an allergic reaction, his system — recognizing a problem — will try to flush out the allergens. One sign: diarrhea. Other signs to look for in the case diarrhea is caused by an allergic reaction: runny eyes, sneezing, constant licking of the paws, chewing on paws, increased scratching, particularly around the base of the tail and red, itchy skin that is moist or scabbed.

An allergic reaction can be triggered by many things; you’ll need to work with  your veterinarian to figure out what substance is the source. Read more about pet skin allergies.

Hair bows

7. Ate a Foreign Object

A dog’s curiosity can lead to the consumption of some very interesting objects. Unfortunately, many of these foreign objects can become lodged in your dog’s stomach or lower intestines and pose a grave threat to his life. Diarrhea is commonly associated with foreign body obstruction. Other signs to watch for: vomiting, abdominal tenderness or pain, lack of appetite, constipation, lethargy and aggressive behavior when touched.

While this is very serious, your veterinarian can quickly determine if this is the problem. Read more about foreign body ingestion threatens pets. Check out our Hambone Award nominees, real stories about dogs who ate shocking objects and lived to tell their tale. 

8.  Irritable Bowel Disease

Irritable bowel disease happens when inflammatory cells chronically invade your dog’s intestine. The cause is unknown. The most common symptom of IBD, when the colon is involved, is diarrhea. One other sign of IBD is weight loss. Your veterinarian can diagnose the condition and discuss a treatment plan to get your dog back to good health.

Ibuprofen tablets

9.  Side Effect of Medication

Your dog’s prescription may cause diarrhea as a side effect. Medications that cause diarrhea include NMDA receptor blockers and NSAIDS (non-steroidal anti-inflammatories used for pain relief) such as Rimadyl and Metacam and Meloxicam. Often, it is the adhesive additive — the binding substance (like lactose) that has been added to the medication that is causing the diarrhea. Learn more about toxic medications for pets.

Be sure to discuss any side effects with your veterinarian as a change in medication may be beneficial.

10. Kidney or Liver Disease

Diarrhea is a common symptom of dogs with kidney or liver disease. Causes of kidney disease include age, trauma, toxic ingestion, cancer, parasites, amyloidosis (abnormal deposits of protein in the kidney), congenital disorders and bacterial infections. Other signs of a serious health issue include a hunched over posture, not wanting to move, weight loss, vomiting, blood present in urine, lack of appetite and an increase or decrease in urine.

A visit with your veterinarian will help determine the exact cause of your dog’s diarrhea. Don’t wait to schedule an exam if the problem persists for more than a couple of days.